10 Worst Things That Have Happened To The Joker
4. Being Replaced - Various Comics
Though imitation is the sincerest form of flattery, the Clown Prince of Crime appears to have a strong policy against anyone attempting to replicate him.
As every single fake Joker that the jester has ever come across has been subjected to a cruel fate by the joker - either via him setting them up to get killed, or otherwise doing the job himself.
Even years down the line he's accomplishing this, as in the fourth issue of Damian: Son of Batman, Joker is still killing off anyone who tries to emulate him, shooting the wannabe supervillain who tries to carry on his legacy having presumed him dead.
Even the copy Joker was nicest to - a man named Edwin who changed into a Joker-doppelganger to try and date Harley Quinn - he still purposefully put into a deadly situation. Having learnt how to be exactly like the jester from the man himself, Edwin would try and convince Quinn that he was the Joker, and wanted a life with her, only for Harley to recognise that his genitals were different to her former paramour, and to murder Edwin as a result.